In recent years, flat displays such as organic EL display devices have been widely used.
An organic EL (Electro Luminescence) element has advantages such as high visibility due to self-coloring, excellent resistance to impact since it is an all-solid-state display unlike a liquid crystal display device, a high response speed, little influence from changes in temperature, a wide viewing angle, and the like, and thus use of the element as a light emitting element in a display device has been receiving attention.
In an organic EL display, like a liquid crystal display, driving methods include a simple matrix method and an active matrix method. While the former has a simple structure, it has problems of difficulty realizing large-scale and high-definition display, and thus the active matrix method is currently being actively developed. In this method, a current flowing into a light emitting element inside each pixel circuit is controlled by an active element (generally, a thin-film transistor (TFT)) provided inside the pixel circuit.